1. Spectroscopic and Ab Initio Studies of the HBF Free Radical Fumie X. Sunahori and Dennis J. Clouthier Department of Chemistry, University of Kentucky Stuart Carter Department of Chemistry, University of Reading Funding: National Science Foundation

2. Motivation  Boron trihalides: precursors for chemical vapor deposition and plasma etching processes Aluminum Layer Mask Silicon wafer

3. Background  # of HBF valence electrons = 11  GS electronic config. [core] (a  ) 2 (a) 2 (a) 1  Nonlinear  ES electronic config. [core] (a  ) 2 (a) 2 (a  ) 1  Linear

4. Ab Initio Calculations Ground State 2 A'Excited State 2 A" 121° 1.20 Å 1.31 Å1.17 Å1.31 Å Band Origin = 10,104 cm -1 Selection Rules:  J = 0, ±1;  K a = ±1;  K c = 0, ±2 [CCSD(T)/aug-cc-pVTZ]

5. Production of HBF/DBF Gas Mixture: BF 3 and H 2 /D 2 in Ar

6. Analysis of Emission Spectra HBF/DBF ExptTheory υ2υ2 993/7711008/778 υ3υ3 1311/12951320/1305 F(J,K a ) = (A-B)K a 2 + BJ(J+1) ˉˉ K a " = 0 K a " = 2 K a ' = 1  K a = ±1 4(A-B) - Expt: 78.0(2) cm -1 Theory: 72.4 cm -1 -

7. Low-Resolution LIF Dissociation to H + BF v = ?? Bond Angle Change 121º to 180º  Transitions to high  2 ' HBF DBF  ??

8. Theoretical Study of PES  Variational method used to predict rovibrational energy levels in the ground and excited states

9. Theoretical Study 1.Calculate energies at various geometries [CCSD(T)/aug-cc- pVTZ]: θ = 90 - 180º; r H-B = 0.76 – 1.32 Å; r B-F = 1.02 – 1.42 Å  Potential energy surfaces (PESs) for the X 2 A' and A 2 A" states 2.Fit the data points using a symmetry restricted polynomial expansion 3.RVIB3 program generates rovibronic energy levels by solving the corresponding Schrödinger equation variationally: (Ĥ N + V e + Ĥ SO )|  > = E|  > ˆ

10. Vibronic Structure

11. Isotope Shifts (H 10 BF-H 11 BF/ D 10 BF-D 11 BF)

12. High-Resolution LIF (HBF) Asymmetry Splitting (K  0) N Asymmetry Splitting (K  0) Spin Splitting  K 2 /N Π(0,8,0) - (0,0,0)  (0,7,0) - (0,0,0)

13. Rotational Analysis Results (HBF/DBF) A(0,7,0) K = 0A(0,8,0) K = 1 B 1.0832(3) B 1.10799(7) 10 5 D 1.5(5) A 0.960(6) 10 3 γ 5.5(7) q -0.0181(1) T 0 15263.240(3)T0T0 15910.723(3) Std. Dev.0.00880.0233 AA 19.5883(8)/ 11.7505(7) BB 1.2033(2)/ 1.0343(3) CC 1.1280(2)/ 0.9461(3)  aa  0.161(2)/ 0.097(3) Std. Dev. 0.0063/ 0.0051 Ground State Excited State A(0,7,1) K = 0A(0,11,0) K = 2 B 0.8855(1) B 0.937(1) 10 5 D 1.5 A -0.12(2) 10 3 γ 2.4(13) q 0 T 0 15338.262(6)T0T0 16080.97(2) Std. Dev.0.02270.0516 ˜˜ ˜˜ HBF DBF

14. Molecular Structure X 2 A' HBF ˜ 1.214(2) Å [1.203 Å] 1.3033(5) Å [1.3092 Å] 120.7(1) º [121.1 º] ˜ HCN A 1 A" 125.0º HCO X 2 A' 124.95º HNO A 1 A" 116.3º HCF A 1 A" 127.2º HNF A 2 A' 125º ˜ ˜ ˜ ˜

15. Current Research 1.214(2) Å [1.203 Å] 1.3033(5) Å [1.3092 Å] 120.7(1) º [121.1 º] [1.191 Å] [1.724 Å] [1.190 Å][1.872 Å] [123.3 º] [123.8 º]